There could be some biological basis. There is strong evidence that nicotine has protective effects and can alleviate symptoms for people with schizophrenia. Something like 60-90 percent of people with schizophrenia smoke.

There've also been some recent studies that found significant genetic overlap between bipolar and schizophrenia, which probably comes as no surprise to the many people who were misdiagnosed as schizophrenic due to psychotic features during a manic or depressed episode. Less research has been done on bipolar and nicotine than has been done on schizophrenia and nicotine, but nicotine does effect dopamine transmission and could likely have an effect on the symptoms of both.

Personally, nicotine is reeeeeally stimulating for me so I love it when I'm manic but have little to no interest in smoking at all the rest of the time.